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  <title>Document</title>
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  <script>
    console.log("" + 1 + 0);// '10'
    console.log("" - 1 + 0);//-1
    console.log(true + false);//1
    console.log(6 / "3");//2
    console.log("2" * "3");//6
    console.log(4 + 5 + "px"); // 9px
    console.log("$" + 4 + 5); // &45
    console.log("4" - 2); // 2
    console.log("4px" - 2); // NaN
    console.log(7 / 0);
    console.log("  -9  " + 5); // 
    console.log("  -9  " - 5);
    console.log(null + 1); // 1
    console.log(undefined + 1); // NaN
    console.log(" \t \n" - 2); 
  </script>
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